Wireless infrared data communications are standardized by the Infrared Data Association (IrDA) in a series of published specifications. IrDA specifications support a wide range of data rates (i.e., from 9.6 kbps to 16 Mbps) in three data rate modes (i.e., SIR or Serial Infrared up to 115.2 kbps, FIR or Fast Infrared up to 4 Mbps, and VFIR or Very Fast Infrared up to 16 Mbps). IrDA supports a wide range of radiant signal intensities at the output of wireless transmitters, 3.6 to 500 mW/sr in two power modes (i.e. low and standard). IrDA also supports communication distances from zero to one meter.
In view of the wide-ranging data rates, signal intensities, and transmission distances supported by IrDA, IR receivers must accommodate a wide dynamic range of inputs over a wide frequency bandwidth. This may be accomplished, in part, using variable gain amplification. In the case of minimal irradiance, IR receivers must be configured for maximum gain in order to identify data transmissions. However, when configured for maximum gain, IR receivers become increasingly susceptible to erroneous signal transitions as a result of power supply noise.
The performance of a circuit in rejecting power supply noise may be quantified as a power supply rejection ratio (PSRR). Poor PSRR performance by an IR receiver may result in a phenomenon known as “dark bits,” which are unwanted pulses that are generated by the receiver when no optical signal has been received. Unwanted amplification of noise, resulting in the unwanted generation of dark bits, becomes more prevalent as a receiver's bandwidth increases to accommodate increased data rates.